The present invention relates to laundry detergents, and more particularly to laundry detergent formulations that include at least one quaternary polysiloxane compound.
Drum-type washing machines which are common in European households, generally wash in two operations. In the main wash cycle, the laundry is first cleaned by means of a detergent (powder or liquid). The main wash cycle is typically followed by two or more rinses with clear water. A fabric softener may be added to the last of these rinses for the purpose of after-treatment. The softener is intended to give the laundry a soft, fleecy feel.
It is known that laundry detergent formulations based on anionic, nonionic and/or amphoteric surfactants, although they clean the laundry, do not have a sufficient softening effect on the textiles. If the consumer desires soft textiles after the wash, then the textiles must pass through a further softening cycle after the main wash cycle.
Attempts to combine the two laundry treatments in one operation in order to spare the housewife multiple dosing have already been made in large numbers.
Various classes of compounds may be used in order to bring about a softening effect in textiles. In the majority of cases, however, cationic surfactants are used, since the preparation of cationic surfactants is cheap and such surfactants produce a softening effect on the textiles even at very low concentrations.
The use of cationic and anionic surfactants simultaneously in order to obtain both a cleaning effect and a softening effect during the wash is generally accompanied, however, by the formation of anion-cation complexes, which not only reduce the cleaning effect of the laundry detergent, but at the same time reduce the desired softening effect.
In order to avoid the formation of an anion-cation complex, the wash cycle and softening cycle are usually performed at separate times.
The consumer is now to be provided with a product which is easier to handle and which replaces multiple dosing operations by a dosing operation which need only be carried out once.
EP-A-0 151 938 describes, for example, xe2x80x9ctwo in onexe2x80x9d laundry detergent formulations, in which anionic surfactants and quaternary alkyl ammonium surfactants are combined with the aid of carrier materials.
In this case, direct contact between anionic and quaternary surfactants is prevented by the quaternary surfactants being present in a form in which they are adsorbed on the carrier materials. The carrier/quat system which goes onto the fiber in the washing operation is separated only after the anionic surfactants have been rinsed out.
Such systems have the disadvantage, however, that the softening effect is observable only to a limited extend in comparison with the separate dosing of fabric softeners. It is desirable, furthermore, to provide homogeneous systems in which the carrier materials do not need to be given long-term stabilization by means of further auxiliaries.
In addition, polydimethylsiloxanes may be used as a softening component in two-in-one laundry detergent formulations. If it is desired to combine the washing operation and softening operation, however, such formulations have the disadvantage that polydimethylsiloxanes, owing to their high hydrophobicity and oleophobicity, lead to deposits and build-up effects in the washing machine and on the laundry.
When the polydimethyl siloxones are deposited or built-up on the laundry, this has the effect of greatly reducing the wettability of the fiber by body moisture and of giving an unpleasant xe2x80x9cgreasyxe2x80x9d feel on the skin after just a few applications.
Quaternary polysiloxanes are likewise known and are described, for example, in EP-A-0 282 720 and in DE-A-37 19 086. Such compounds have been known to date for their conditioning properties in hair cosmetology.
The skilled worker does not expect such quaternary poly-siloxanes to be combinable with anionic surfactants, since anion-cation complexes ought to occur.
It is the object of the present invention to provide laundry detergent formulations which combine the washing operation and softening operation and which after the wash leave a distinctly measurable softening effect in the textiles.
It has surprisingly now been found that the addition of quaternary polysiloxanes to anionic laundry detergent formulations leaves a distinctly measurable softening effect on the textiles but does not exhibit any visible precipitate of anion-cation complexes or build-up effect on the treated laundry. A further advantage is that the quaternary polysiloxanes used in accordance with the present invention are compatible with the detergent substances that are commonly used, and normally require no additional auxiliaries for incorporation.
The present invention accordingly provides for the use of quaternary polysiloxanes of the general formula (I) 
and/or
cyclic quaternary polysiloxanes of the general formula (IIa) 
and/or
linear quaternary polysiloxanes of the general formula (IIb) 
where
M is a divalent hydrocarbon radical of at least 4 carbon atoms which contains a hydroxyl group and may be interrupted by at least one oxygen atom, the nitrogen atom of the radical Z being connected to the radical M via the carbon atom adjacent to the Cxe2x80x94OH group in the radical M,
Z is a radical 
R1, R2, R3=alkyl radicals of 1 to 22 carbon atoms or alkenyl radicals of 2 to 22 carbon atoms, it is possible for the alkyl or alkenyl radicals to contain hydroxyl groups, and at least one of the radicals R1, R2 and R3 has at least 10 carbon atoms,
R4, R5, R7, R9, R10=alkyl radicals of 1 to 22 carbon atoms or alkenyl radicals of 2 to 22 carbon atoms, it is possible for the alkyl or alkenyl radicals to contain hydroxyl groups,
R6=xe2x80x94Oxe2x80x94 or xe2x80x94NR8xe2x80x94radical,
R8=alkyl or hydroxyalkyl radical of 1 to 4 carbon atoms or hydrogen,
x=2to 4,
n=a number from 0 to 200,
Axe2x88x92=an organic or inorganic anion originating from a customary physiologically acceptable acid HA,
Z1=an H, OH, alkyl or alkoxy radical, or has the definition of a hydrocarbon radical of at least 4 carbon atoms which contains one or more hydroxyl groups and may be interrupted by one or more oxygen atoms, or has the definition of the radical 
Z2=the group 
Y=a divalent hydrocarbon radical of at least 2 carbon atoms which may contain a hydroxyl group and which may be interrupted by at least one oxygen or nitrogen atom,
R11, R12, R13, R14=identical or different and are alkyl radicals of 1 to 4 carbon atoms or benzyl radicals or in each case R11 and R13 or R12 and R14 may be components of a bridging alkylene radical,
R15=an alkyl radical of 1 to 20 carbon atoms,
m=integer greater than or equal to 1,
in laundry detergent formulations.